The invention relates to a method of testing a structural component having a complex surface contour by means of ultrasound, at least one ultrasonic head being guided along the surface contour of the structural component by means of a manipulator having several axial drives in several axes at a defined spacing and equidistant pulses being generated as trigger signals for the geometrically correct allocation of received ultrasonic test data for the surface contour of the structural component according to the movement of at least one drive, as well as to a device for testing a structural component having a complex surface contour, comprising a manipulator that displaceable along one or more axes by means of axial drives, at least one ultrasonic head being movable with said manipulator at a defined distance along the surface contour of the structural component, the axial drive being controllable by means of a control and at least one encoder being provided for generating trigger pulses for the geometrically correct allocation of received ultrasonic test data to the surface contour of the structural component.
A method of testing a structural component having a complex surface contour by means of ultrasound is known from an internal state of the art, wherein, on a conventional multiaxial test manipulator, one or more ultrasonic transmitter are arranged which travel along a straight or slightly curved surface contour of a structural component for testing the latter. At least one axial drive of the manipulator is equipped with preferably an optical encoder for generating trigger pulses for an ultrasonic control unit. Each encoder is respectively allocated to a principal axis, such as an X axis. In an automated test of the structural component, the encoder generates equidistant pulses according to the movement of the associated axial drive for a motion vector of the associated axis. The equidistant pulses are necessary as triggers for the geometrically correct allocation of the ultrasonic test data to the test part.
A device 10 having a uniaxial trigger system according to this prior art is shown in FIG. 1. The device 10 comprises a multiaxial manipulator 12, each axis, such as e.g. the X axis, Y axis, Z axis and, perhaps, axes of rotation such as an A axis or B axis, being associated with a drive MX, MY, MZ, MA, MB, controllable by corresponding control cards SX, SY, SZ, SA, SB via a numerically controlled system NCS. One of the axial drives, in the illustrated example the drive MX of the X axis, is coupled with an encoder E which, corresponding to the movement of the associated axial drive, transmits equidistant pulses to an ultrasonic system USS. The trigger pulses are thereby generated in proportion to the advance along the linear X axis. The ultrasonic system USS is coupled with a control computer SR which is, in turn, connected with the numerically controlled system of the multiple manipulator.
If the geometry of the surface contour of the structural component to be tested is curved in a complex manner in the main direction of testing, a sufficient accuracy of the true-to-surface data recordal cannot be guaranteed with a uniaxial triggering. In this sense, true-to-surface data recordal means that an equidistant test point grid on the surface of the structural component is provided as a fixed C image for later reproduction of the measurement results.
A calibration method for a three-dimensional shape-detection system and a system for carrying out that method are described in DE-T 690 03 090. The described calibration method aims to create a new calibration method which is independent of the structure of a sensor unit and, accordingly, does not require a prior physical measurement of geometrical parameters. With the method, the knowledge of the geometric parameters of the sensor unit is replaced by a calibrating object that is easy to dimension. The set-up of an intermediate transfer function takes place directly by detecting the raw information under the same conditions as the later measurement of the points of an object, so that an error accumulation can thus be avoided.
EP-A 0 489 161 relates to an ultrasonic crack detector. Distance sensors and an ultrasonic head are connected to one another as a uniform structure, so that the distance sensor is connected, together with the ultrasonic head, over the scanning lines. The surface scanning of an object W by means of the distance sensor is effected in parallel with the crack detection by the ultrasonic head. The crack detection area is subdivided into a plurality of smaller areas, a plurality of storage areas similar to a net are saved in a storage unit. Only one surface value of the position storage area contains the crack detection area and is stored in each of the storage areas. Based on these stored form data, the position and the angle or position of the ultrasonic head can be controlled in each of the crack detection points.